R1150RT Fuel Gauge Sensor Testing

[MarkAZ]

I'm getting ready to re-assemble the fuel tank for my R1150RT and want to test the fuel level sensor first. I'm assuming that it uses a resistive element so the resistance would change as the float slides up & down. Any idea what the resistance range should be? Mine appears to only change a few ohms from bottom to top, like between about 74 and 71 ohms.That doesn't seem like much of a range. Is it possible to CAREFULLY open it up? There appears to be a little nut on the bottom so I'm wondering if removing that would allow the tube to slide off to expose the element. Perhaps the sliding element is not making good contact. Thanks...

[dirtrider]

12 hours ago, MarkAZ said:

I'm getting ready to re-assemble the fuel tank for my R1150RT and want to test the fuel level sensor first. I'm assuming that it uses a resistive element so the resistance would change as the float slides up & down. Any idea what the resistance range should be? Mine appears to only change a few ohms from bottom to top, like between about 74 and 71 ohms.That doesn't seem like much of a range. Is it possible to CAREFULLY open it up? There appears to be a little nut on the bottom so I'm wondering if removing that would allow the tube to slide off to expose the element. Perhaps the sliding element is not making good contact. Thanks...

Morning Mark 

 

Do not open it up if you can avoid it as it is very easy to damage the stretched wires. 

 

You don't have a dent in the side of the sender tube do you? If so that is caused by a plugged tank vent (or plugged evap can) allowing the in-tank vacuum to suck the fuel tank sides in therefore crushing the tube. A dent in the tube can prevent the float from full travel. 

 

I have also seen oxidation/varnish on the stretched wires inside the tube causing resistance issues. Using Techron in the fuel for a few fill-ups can sometimes clean the internal resistance wires. 

 

On the resistance measurements? I have it written down in my shop but I am not near my shop this weekend. If I remember correctly about 75-80 ohms empty tank & around 3.6 ohms (give or take)  full tank.  

 

If yours is stuck at 74 ohms then it sounds like your float is stuck at the bottom of the tube. (possibly try some WD-40 inside the tube  then lightly tapping the inverted tube. 

 

If your tube has a dent in it then that needs to be removed (without hurting the resistor wires inside the tube). If you have a dent then post back for info on how to remove that. 

 

 

[MarkAZ]

Thanks, DR...

 

No dents in the tube. I can hear the float moving and hitting top & bottom when I tilt it so I don't think the float is stuck. The way I understand it working is that there are two resistor wires that run parallel and the float shorts them out so at the top (full tank) there's very little resistance but at the bottom (empty) it's the full resistance. The bike has sat for a few years and the gas in the tank was very skunky so I suspect corrosion of the float contact. Last time I ran it was about a year ago and the gauge worked then, it had about four gallons in it. I have it apart to clean the tank and replace the fuel pump, filter, hoses, etc. The filter sock was completely disintegrated, I suspect the pump ingested some pieces of it, so I wouldn't be surprised if the sensor was damaged as well by the yucky fuel. I'll dink with it some more but I suspect I'll have to take it apart eventually. Or just say to hell with it & go without a working fuel gauge...none of the other bikes I've owned have had one & I can just monitor the mileage between fill-ups. We'll see....

[dirtrider]

10 minutes ago, MarkAZ said:

Thanks, DR...

 

No dents in the tube. I can hear the float moving and hitting top & bottom when I tilt it so I don't think the float is stuck. The way I understand it working is that there are two resistor wires that run parallel and the float shorts them out so at the top (full tank) there's very little resistance but at the bottom (empty) it's the full resistance. The bike has sat for a few years and the gas in the tank was very skunky so I suspect corrosion of the float contact. Last time I ran it was about a year ago and the gauge worked then, it had about four gallons in it. I have it apart to clean the tank and replace the fuel pump, filter, hoses, etc. The filter sock was completely disintegrated, I suspect the pump ingested some pieces of it, so I wouldn't be surprised if the sensor was damaged as well by the yucky fuel. I'll dink with it some more but I suspect I'll have to take it apart eventually. Or just say to hell with it & go without a working fuel gauge...none of the other bikes I've owned have had one & I can just monitor the mileage between fill-ups. We'll see....

Afternoon Mark

 

Squirt  some WD-40 inside the float tube. Then flip the tube over & over to allow the float to slide top to bottom.

 

If that doesn't work then wash the float tube out with gasoline then squirt some Techron in then flip the tube over & over to allow the float to slide top to bottom.

 

It will probably start working once you get it to clean the internal resistor wires float contacts.